Thesensationofbreathingeffortisthoughttobetheresultofacomplexintegra- tion ofdifferentsensoryinputsincludingchemical-,mechanical- andneural-based signals.Wewishedtoexplorethedeterminants ofbreathingeffortsensation(BES) duringexhaustingexerciseinnormobaricnormoxiaandhypobarichypoxia.Eleven non-smokinghealthymalesubjects(age41[14],mean[SD]yr)werestudiedduring incrementalcycleexercise(30watt/3min)untilexhaustion(WLmax)atsealevel (SL)andafter2-3daysat4559meters(ALT).WemeasuredBES(Borgscale), ventilation(V’E),tidalvolume(Vt),respiratoryrate(RR),oxygensaturation(Sat), workofbreathing(fromdynamicesophagealpressure-volumeloops,WOB),total breathingmechanicalpoweroutput(W’=WOB*RR)andenergycostofbreathing perunitventilation(WOB/V’E). ComparedtoSL,atALTV’EandSatwerehigher(p<0.001forboth)foranywork- load.WLmaxwas15[8]%lowerthanSL(p<0.001).TheBESvsV’Erelationship wassimilaratALTcomparedtoSL.WithincreasingV’E,W’wasprogressively loweratALTthanatSL(p<0.001)asaconsequenceofaprogressivelyreduced flowresistivework.BeyondV’E>∼50 L/minBESwasprogressivelyhigherat ALTcomparedtoSLforagivenWOB/V’E.Yet,thechangesofVtandRR remainedsimilaratanylevelofventilationonbothconditions. In conclusionbreathingeffortsensationappearsuniquelyrelatedtoventilation, despitethedifferencesincostofbreathingandmetabolicrequirementsatALTand SL.
Determinants of breathing effort sensation in normoxia and hypobaric hypoxia
POMIDORI, Luca;COGO, Annaluisa;
2009
Abstract
Thesensationofbreathingeffortisthoughttobetheresultofacomplexintegra- tion ofdifferentsensoryinputsincludingchemical-,mechanical- andneural-based signals.Wewishedtoexplorethedeterminants ofbreathingeffortsensation(BES) duringexhaustingexerciseinnormobaricnormoxiaandhypobarichypoxia.Eleven non-smokinghealthymalesubjects(age41[14],mean[SD]yr)werestudiedduring incrementalcycleexercise(30watt/3min)untilexhaustion(WLmax)atsealevel (SL)andafter2-3daysat4559meters(ALT).WemeasuredBES(Borgscale), ventilation(V’E),tidalvolume(Vt),respiratoryrate(RR),oxygensaturation(Sat), workofbreathing(fromdynamicesophagealpressure-volumeloops,WOB),total breathingmechanicalpoweroutput(W’=WOB*RR)andenergycostofbreathing perunitventilation(WOB/V’E). ComparedtoSL,atALTV’EandSatwerehigher(p<0.001forboth)foranywork- load.WLmaxwas15[8]%lowerthanSL(p<0.001).TheBESvsV’Erelationship wassimilaratALTcomparedtoSL.WithincreasingV’E,W’wasprogressively loweratALTthanatSL(p<0.001)asaconsequenceofaprogressivelyreduced flowresistivework.BeyondV’E>∼50 L/minBESwasprogressivelyhigherat ALTcomparedtoSLforagivenWOB/V’E.Yet,thechangesofVtandRR remainedsimilaratanylevelofventilationonbothconditions. In conclusionbreathingeffortsensationappearsuniquelyrelatedtoventilation, despitethedifferencesincostofbreathingandmetabolicrequirementsatALTand SL.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
